The desirability of facilitating the harvest of various agricultural crops, especially fruit crops such as citrus fruits, is readily apparent. A number of chemical compounds capable of promoting fruit abscission has been proposed, which compounds serve to reduce the pull force necessary to remove mature fruit from the tree or plant, thus rendering mechanical harvesting practical. Few of these compounds, however, have found practical utility, mainly owing to their tendency to injure immature fruit and cause blossom drop and/or their simultaneous defoliant effect.
One compound suggested for use as a citrus fruit abscission agent is 5-chloro-3-methyl-4-nitro-1H-pyrazole, i.e., ##STR1## This compound and its use are described more fully in U.S. Pat. No. 3,869,274. While the compound is indeed effective in reducing the pull force necessary to remove citrus fruit from trees, its use in concentrations effective to cause abscission often results in excessive damage to the mature fruit being harvested, leading to post harvest disease and/or "off" taste in fruit juices made therefrom.